Baby's first type checker
10 days ago
- #Python
- #Programming
- #Type Checking
- Python allows optional type annotations for variables and functions, aiding in type checking.
- Type checking in Python can be performed using third-party tools like Mypy, Pyright, or Pyrefly since Python lacks a built-in type checker.
- A baby type checker can be built to parse Python code, identify type annotations, and verify type compatibility.
- The type checker supports primitive types, containers (lists, dictionaries), functions, unions, and type narrowing.
- Type narrowing refines variable types within control flow branches based on conditions like isinstance checks or None comparisons.
- The baby type checker is implemented in about 350 lines of Python, demonstrating core type checking concepts.
- Future enhancements could include generics, type variables, structural subtyping, and more sophisticated type inference.